Electrical sound transmitting and receiving apparatus



l 1",s33,17o H. FISCHER f l June 21 ,A 1927.

Y ELECTRICAL SOUND TRANSMITTING AAND lRECEIfvINci APPARATUS Filed oct. 12, 1925 15 soun transmitting apparatus constructed in ratenteaylune -z1, '1927.

UNITsD-fsTA'rEs 1,633,170 .PATENT OFFIOE.

HERMANN FISCHER, or N EwyoRx, l1s. T., AssIGNOR To TOWER MANUFACTURING CORPORATION, or BOSTON, afneissiicnusarTs,` A. CORPORATIONO 1'1 MAssAcnUsETTs.

praemien soU'Nn TRANSMITTING' AND- Racarvnfe ArrmTusI Application mea otb'er`ia ,.19a5. serial R9. 62,075.

The objectof the vpresent invention is t' provide a sound receiving or ltransrnittin apparatus employing .'a diaphragm actuated, by electricwaves or impulses in'conuntion 6 with4 means for securing reaotionjof the diaphragm -under conditions ideal for both` the high tones andthe low tones of the scale' and for reproduction of said tones without' distortion.

The invention' Will` be.. understood by reference tothe following 'specificationin connection with the' a'cconipanyingdrawing, in which- Fi ure 1 1s 'a sectional elevation of-'a accordance with the improvement;

- Figure 2 isa fragmentary plan View of the apparatus; and f v Figure -3 isadiagrammati view in plan andtr'ansverse section4 illustrating amodified form-of apparatus within the invention.

Referring to the drawings, the embodiment illustrated in Fi esil and 2 com-` prises a casing A, having a lower annular member 1 and anvupper annular member 2, the two at their outer marginal faces being threaded to receive a. connecting ring 3. Clamped between members 1 and2 1s a .diaphragm 4.. Intermediate its length.the *z'diaphragm restsl upn the .annularly` art ranged points 5"` of a cup-shaped member 6 threaded within casing member 1. The .cup

6 encloses an electromagnet having the poles v7, the magnet beingenergized through the'- wires 8 leading to the means for vreceiving the sound" vibrations, -1 assuming that the apparatus illustrated 'in the figure is employe as ay sound receiving and reproducing in strument, as for example the loudspeaker of 40 a radio'receivingapparatus..

Opposite the points 5x ofA cup 6 are like. points 9 of an annular member 10 threaded within casing member 2.l Points 9 are in contact with the diaphragrni." Member 10.

is providedwith an outlet 10? forthe sound vibrations, to which outlet may be connected a horn or other amplifying device, if desired. i The diaphragm 4 in the embodiment ofv the'invention illustrated. in Figures 1 and 2 of the drawing is'so mounted as to have acentral portion, bounded' by the points 5", 9,

of less area than thesurroundin portion, and the said central portion is a apted for reproduction-of the high .notes of the scale represented `-by rapid-vibrations which are relatively strong.. 'That portion of the diaphragm exterior thewpointsv 5", `9, provides meansfor'acting upomthe low notes of the scale, represented in a receiving device by 'slow vibrations which are relatively. weak. Notes which would be damped or distorted bythe 'fact that the diaphragm line between fthe polerpieces and the points 9, is too short for theirslow vibration and low force,

will be ideally reproduced by therelatively wide and flexible area of the vdiaphragm surrounding thesaid points. Furthermore, the points 5", 9 act as fuicrumsto enable the magnicationof vibrations exerted 'upon the diaphragm 'at the centre thereof, the vibra- "tions increasing in length from the points to the line aryx, Figure 1, and then decreasing toward the outer surface of the diaphragm. Not only are over-tones reproduced whichin ordinary reproducing devices 'are entirely damped and lost, but the-volume of repro-l duction is very greatly increased by the invention.

It will be understood that various modi- :of the diaphragm tothe right of the points 41 2, 12c provides means for acting lupon the high notes of the scale and that portion of the diaphragm to the left of the points provides means for acting upon the 1 ow notes of the scale having less resistance to the ac-. tion of magnetic waves. .The-pole pieces act To .the

. icationsmay be made in-:the embodiment of the 'invention illustrated in Figures 1 and with greater leverage `upon the larger area Y to the left of the points, the points acting 'as fulcrum members. The casing may be shaped asdesired, as

also the diaphragm. For example, the casf ing and -diaphragmmay be shaped in an 14, Figure 3.

The annular line of ulcrum points may be substituted by upper and lower rings,

each having a somewhat sharpedge contacting with the diaphragm. Also in the constructionshown in' Figure 3, the points may be substitutedby straight sharp-edge fulcrum bars one at the top and one at the bottom .of the diaphragm the sharp edges directly engaging the latter.

The centre portion of the diaphragm may be of magnetic material and the'surrounding portion of non-magnetic material.` For example` the centre portion may be iron, and the outer portion fibre, Wood or a composiL tion or some other non-magnetic material, or even of magnetic material (littering in vibratory characteristics from the iron and suitably connected to the centre portion. Also` the centre portion' may be non-magnetic and connected by a needle or other means with a primary ,-vibrato'rydiaphragm'.y lt desired, the outer edge of the diaphragm 25 may be left free, or the diamhragm may be members for the opposite 'faces of the diai' phragm disposedA intermediate the" pole piece of the magnet and the outer margin of the diaphragm and dividing the latter into two zones. the lesser zone being 4intermediate the magnet and thefulcrum members.

2. In electrical sound transmitting and receiving apparatus, aeasing, an electromagnet, a diaphragm Within the casing` co-acting ulcrum devices for the opposite faces ot' the diaphragm intermediate a lesser area thereotl directly acted upon by themagnet and a' ,greater area reactively' actuated through the vibrations of the lesser area.

ln testimonywhereof, I have Signed my name to thisspecication.

HERMANN FISCHER.

points aroundy its', pe-

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